The Pakistani Taliban has claimed responsibility for a suicide bomb attack in the eastern city of Lahore that killed at least 25 people and injured more than 250.

The attack is widely seen as the Taliban's response to the Pakistani government's ongoing operation against extremists in the northwestern Swat region. A recent string of high-profile militant attacks in Lahore suggest that Pakistan's war against the insurgents has now expanded into its heartland.

Militant commander Hakimullah Mehsud, often described as the deputy of key Pakistani Taliban leader Baitullah Mehsud, claimed responsibility for the May 27 attack in Lahore.

In telephone calls to Western media, Mehsud also warned more attacks were to follow against government targets in major cities across Pakistan.

In the brazen mid-morning assault in Lahore, attackers using guns, grenades, and a van packed with explosives targeted a compound that housed several official buildings, including the office of Pakistan's premier intelligence agency, Inter-Services Intelligence (ISI).

The ferocity of the blast from the van turned a small intersection in Pakistan's second-largest city into a war zone, leaving a massive crater, destroyed buildings, and crumpled cars in its aftermath. Lahore-based regional expert and author Ahmed Rashid describes the mood after the bombing as one of "shock and anger."

Rashid says such attacks were expected after the Pakistani military launched a major operation against extremists in the northwestern Swat Valley and the surrounding Malakand region.

"They want to open another front, and they want to frighten the government and the establishment," Rashid notes. "And we were all expecting it much earlier. I'm surprised it took so long."

Opening New Fronts

Pakistani police detain a suspect in the suicide car-bomb attack.

The bombing was the third major attack in recent months in Lahore, a teeming city of 10 million and the capital of Punjab, Pakistan's most populous province.

High-profile attacks on the Sri Lankan cricket team and a police training academy in March that killed dozens were followed by this week's blast, which killed at least 25 people and injured more than 250.

Among the dead and injured were many police and security service officials who were working at the city's police headquarters at the blast site.

The Pakistani government has now announced bounties for the capture and arrest of 21 Taliban commanders in Swat who are accused of revolting against the state. The government claims to have killed more than 1,000 insurgents in Swat this month.

But the Taliban is reportedly digging in, laying land mines in their western Waziristan stronghold in the anticipation of a summer offensive. Rashid says he believes the Taliban is seeking to open new fronts in order to increase the burden on Pakistani security forces.

"The Taliban's interest is to stretch the army and relieve pressure on Swat to some extent," Rashid says. "And that's why there have been attacks in the [northwestern] city of Peshawar and in [the Federally Administered Tribal Areas] FATA and now in Lahore and maybe in other parts of Punjab."

Two bombs exploded on May 28 in a fresh attack on Peshawar. Some casualties have been reported.

Malik reiterated, however, his government's resolve to fight the insurgency. He said the government "listened to everything" the militants said, and even implemented Shari'a law. But there will be "no discussion and no negotiations with the militants now."

Most Pakistani analysts agree that the war in Pakistan will expand this summer unless the military achieves a decisive military victory against the Taliban in Swat and Malakand soon.